Heating oil



Tf? Il, EM?. l A. Q. CATOYETAL 294179236 HEATING on.

Filed Jan. 2,

34"" rfi-f ATTORNEY Patented Mar. 11, 194i HEATING OIL Artie Q. Cato,Houston, George Wash, Galveston, and Albert J. Shmidl, Houston, Tex.,assignors to Standard Oil Development Company, a corporation of DelawareApplication January 2, 1945, Serial No. 571,100

1 Claim. 1

This application is a continuation-impart of application Serial No.522,124, led February 12, 1944, now Patent No. 2,380,294, issued July10, 1945.

The present invention is directed to a liquid composition particularlyadapted for use as a fuel oil in home heating installations. Moreparticularly, it relates to a composition of good color stability andproduct quality which is produced by blending petroleum heating oilfractions.

Heating oils as mentioned herein will be taken to include petroleum oilfractions boiling up to about 660 F. and having a gravity of at least 30API. The oil should be of at least 10 color as measured by theTag-Robinson color machine` and should have a ash point between about130 and 190 F. Of course, it must be realized that the oil should notcorrode or plug the burning equipment and this tendency is usuallyreflected by an oil passing the suspended sediment and copper stripcorrosion tests.

The conventional treating methods for heating oil fractions in thepetroleum refinery usually include distillation, acid treating, causticwashing and doctor sweetening operations. For economy of equipment it isalways good practice to combine the treating operations such that oilsfrom Various sources are handled in one system of equipment. It would beuneconomical, for example, to segregate each fraction and handle it inits own tankage, distillation, acid treating, caustic Washing and doctorsweetening equipment. In a similar manner it is economical to combinestreams for filtration, which filtration operation is usually requiredto remove from the heating oils suspended matter which, if left toremain in the heating oil, would be objectionable in operation of theheating equipment.

Heating oil fractions boiling up to about 660 F. may be obtained bydistilling either cracked or crude petroleum products. These materialsusually require nishing treatment before they are suitable for use asfuel for heating systems. Heretofore heating oil fractions were obtainedfrom thermally cracked products and from crude petroleum. Thesefractions as mentioned before are amenable to finishing operations whichmay include acid treatment, caustic washing, doctor sweetening, andfinally filtration. However, with the advent of catalytic crackingentirely new handling procedures become necessary since applicants havefound that the conventional methods are not applicable to heating oilfractions from catalytically cracked hydrocarbons. For example, when acatalytically cracked heating oil fraction is admixed with heating oilfractions from thermally cracked products and crude petroleum, theadmixture of the oils is seriously impaired in color when subjected tothe conventional finishing operation which includes treatment with astrong alkaline reagent.

It is, therefore, the main object of the present invention to provide atreating and blending procedure for obtaining a heating oil of goodquality which includes heating oi1 components from crude petroleum,thermally cracked naphtha and catalytically cracked naphtha.

In one specific embodiment of the present invention heating oilfractions, i. e., fractions boiling between about 350 and 700 F. aresegregated from crude petroleum, and mixed with the heating oil fractionfrom a thermal cracking operation after the heating oil fraction fromthe thermal cracking operation has undergone acid treatment, causticneutralization and rerunning to segregate from the acid treated producta fraction similar in boiling range to that obtained from thedistillation of the crude petroleum.

The combined streams are then treated withan alkaline solution, andafter removal of the alkaline solution from the treated oil, the oil isthen doctor sweetened as in conventional practice. Following the doctorsweetening operation the resulting alkali treated and sweetened oil iscombined with a heating oil fraction from a catalytic crackingoperation. It is preferred to pass the mixture through a filtercontaining an adsorbent material, such as fullers earth and the like, asa nal finishing step to insure the removal of foreign bodies, which lmaybe carried by the oil from the previous treating steps. While the finalltering step is essential for the oils which have undergone treatmentwith an alkaline reagent, and is desirable in some instances for the oilfrom the catalytic cracking operation, it is possible to omit thefiltering step for the oil from the catalytic cracking operation andcombine this fraction with the filtered oils and obtain a stable heatingoil of commercial grade.

If the fuel oil fraction from the catalytic cracking step had beenadmixed with the other two streams and the blend contacted with thealkaline solution, a product of greatly Vinferior quality would havebeen obtained. The reason for the unexpected result of the presentinvention is not completely understood, but it is believed that in theheating oil fractions obtained from Vcrude petroleum there are presentcertain4 naphthenic type compounds, which in the presence of alkalinereagents react with the oleinic and aromatic constituents in the heatingoil fraction from the catalytically cracked product. These reactionproducts are dark colored materials which evidently undergopolymerization reactions on storage and cause the oil to darken to atarry appearance and to precipitate sedimentary bodies which plug andfoul straining equipment and the burner tips of heating systems. In thehandling procedure of the present invention these deleterious effectsare not obtained.

By way of explanation, it might be mentioned that catalytic crackingcauses the formation of certain types of hydrocarbons in appreciablylarger quantities than heretofore have been obtained in thermal crackingoperations. These types of hydrocarbon compounds include, among others,the cyclo-olenic hydrocarbons which are quite reactive; furthermore, thecatalytically cracked materials contain appreciable quantities ofhydrocarbons of branch structure which are known to be more reactivethan those consisting essentially of straight chains. It is believedthat these large quantities of cyclo-olenic compounds and hydrocarbonsof branch structure enter into reaction with other types of compoundsquite readily and even more readily in the presence of an alkalinematerial such as used in conventional treating operations in the modernrenery. It is to be understood that the foregoing hypothesis is givenonly by way of explanation for the unusual result of the presentinvention, and not as a restriction or limitation on the scope of theinvention.

The present invention will be further illustrated by reference to thedrawing in which the single figure is a low diagram of a preferred'method of conducting the invention. Y Referring now to the drawing,numeral I I designates a feed line through which a hydrocarbon in thegas oil boiling range is introduced into catalytic cracking unit I2.Catalytic cracking unit I2 may be aV cracking operation such as theso-calledfThermofor. cracking operation, or a fixed bed catalyticcracking operation, r a huid catalyst cracking operation. These severalcatalytic cracking operations have been described elsewhere in thepatent literature and further reference thereto need not be made here.The product issuing from catalytic cracking unit I2 is conductedtherefrom by way of line I3 and discharges into a fractionation zoneIll. Fractionation zone I4 is provided with line I5 for removing anoverhead fraction boiling below 420 F., with line I6 for removal of aheavy gas oil fraction boiling above 600 F. and with line I7 for thedischarge of oil containing small amounts of catalyst when the catalyticcracking operation is of the iiuid catalyst type.

A fraction having heating oil characteristics discharges fromfractionation zone I4 by way of line I8 and may be introduced therebyinto a treating system I9. Treating system IQ may include acid treating,caustic washing, o-r doctor Asweetening operations, or all of them. Whentreating system I9 includes an acid treating step, it must also includea rerunning step for removal of polymers resulting from the acidltreating operation. In a preferred operation, however, treating systemI9 is'by-passed by closing off valve 2li in line I8 and opening valve 2Iin branch line 22, thereby by-passing treating system i9 completely. Inthe cases where treating system I9 is luy-passed,v it will be understoodthat valve 23 in line 24 Will also be closed oi. The heating oil 4fraction from the catalytic cracking `unit routed through line 22 isthen further handled, as wil be described hereinafter.

Operating in parallel with catalytic cracking unit I2 is a thermalcracking unit 25 into which a gas oil fraction is introduced by way ofline 26. rI'he conditions for the satisfactory operation of a thermalcracking unit have been disclosed in detail in the patent literature andwill not be repeated here. The thermally cracked product issuing fromthermal cracking unit 25 discharges by way of line 21 into fractionationzone 28, which is provided with a line 29 for removal of materialboiling below about 400 E'. and line 30 for discharge of materialboiling above about '706 F. Fractionation Zone 28 is also provided withline 3i through which a heating oil fraction discharges into treatingsystem 32. Treating system 32 in this particular instance includes anacid treating system for removal of unstable hydrocarbons from thethermally cracked heating oil fraction. Line 8 serves as a means forinjecting sulfuric acid into treating system 32, and line 9 as a meansfor withdrawing acid sludge therefrom. The acid treated oil issuing fromtreating systemv 32 discharges by way of line 33 into fractionation zone34 which is provided with line 35 for removal of constituents boilingbelow about 400 to 420 F., line 36 for removal of a heavy gas oilfraction and line 3l for discharge of polymerized material resultingfrom the acid treating operation. The heating oil fraction dis- Kcharges from fractionation zone 34 by way ofline vsolution at an optimum38 and is admixed with a heating oil fraction introduced into line 38 byway of line 39 and obtained in a manner to be described.

rI'he heating oil fraction in line v3! is obtained by charging a crudepetroleum fromr crude oil storage tank t0 by Way of line 4I and pump 42into fractionation zone t3. From fractionation zone fl-3, a lightfraction boiling below about 400 to 420 F. is removed by line Mi, .and afraction boiling above the heating oil boiling range is removed by linet5 while the heating oil fraction is withdrawn by line 39. y

The mixture of thermally cracked Vand natural heating oils is conductedby line 38 and is admixed with an alkaline solution, introduced by way'of line d6, in incorporator di' and passed thence by way of line 48vint-o settler '29. Alkaline solution is withdrawn from settler 49 by wayof line 5G. This solution may be recycled 4by lines 5I and t5 to line38. From time to time it will become necessary to discard a po-rtionofthe alkaline reagent discharged from settler d@ bylway of line 53. Thisis accomplished by opening valve 52. In a similar manner fresh alkalinereagent is .introduced by line i5 by opening valve 53 therein. Y n

rIhe alkalineV treated mixture of thermally cracked and natural heatingoils discharges from settler 49 by way of line 51%,has doctor reagentadded thereto by line 55 and passes throughinccrporator 55 and line 5linto settler T5S-which allows gravittl separation between thehydrocarbon phase and the doctor reagent phase. The doctor reagent phasemay be withdrawn by line 59 and recycled to line 54 by way of line 55.As required, from time to time, fresh doctorreagent may be introducedinto the system, by"

opening valve t@ in line 5.5. Spent doctor reagent may be discardedintermittently to maintain'the @I in line 62.

strength by opening valve eration described in connection withincorporator 56 and settler 58 it is usual practice to include alkalinesulde and water washes to remove occluded or suspended lead compoundsfrom the cracking operation and a heating' oil 'fractionl from acatalytic cracking operation were blended together and subjected totreatment with sul-f furic acid and rerun to proper distillation charfdoctor 'sweetened oil. This is usually accom- 5 acteristics. This rerunmaterial was then blended', plished by contacting the doctor treatedhydrowith a heating oil fraction from a crude petrocarbons with a spentcaustic solution which usleum, and similar to the rSt run, was treatedually contains sodium p-olysuliide compounds and with 40 B. causticfollowed by dOCOr SWBEtGYliIlg, is usually followed by washing withwater. sodium polysulfide and water washing, and filtra- Thehydrocarbons issuing from settler 58 by l0 tion. This material was alsotested to deter- Way of line 63 admix with the catalytically mine itscharacteristics. In a third operationan' cracked heating oil fractionfrom line 2| and acid treated and rerun heating oil from the sameoommingle in line te and are introduced thereby thermally crackedoperation as runs one and twov into filter 65. As mentioned before,filter 65 is was admixed with a heating oil ffnet/i011 frOm packed withan adsorbent material such as fulcrude petroleum and SUbJ'GCed t0Similar treat'. lers earth, kieselguhr, bauxite, or other similar mentwith caustic, doctor Sweetening, sodium adsorbents well known to theart. The filtered DOIYSuldE and Water Washing as outlined in the oildischarges from lter 65 by way of line 66 preceding two runs andlikewise submitted to tests and is then suitable for use in heating oilsysto determine its characteristics. A fourth run tems. was made inwhich an acid treated and rerun The final filtering step is desirablefor the heating oil from a thermal cracking Operation. production of anigh grade heating oil but for was admiXed with a heating 011 from acrude operability of the process it is not essential that petroleum andthe admixture then caustic the catalytically cracked heating oilfraction washed, doctor sweetened, sodium polysulde from line 22 bepassed through the filter B5. If it 25 washed and water washed. To thistreated adis desired to omit the filtration of the catalytmixture wasadded a heating oil fraction from` ically cracked fraction, valve 2| inline 22 is a catalytic cracking operation and the resultant closed andvalve 6'! in line 68 opened allowing composition was then filtered. Thisfourth run this fraction to by-pass filter 65 and the filtered is thepreferred embodiment of the present inmixture of the thermally crackedfraction and the vention. crude fraction commingle in line 66 with theThe comparison of the tests obtained on the catalytically crackedfraction introduced thereto materials resulting from the four runs ispreby line 68. The filtering step removes foreign sented in thefollowing table:

Table I Run l 2 3 4 Calci?, 'Iag-Robinson, at various stages of nishing:

ee After treatment With 40 B. sodium hydroxide After 40 B. sodiumhydroxide treatment, doctor sweetening, sodium polysulfide washing,water washing and filtering. Other tests on finished product:

Colorho1d,1 16 hours at 212 F Corrosion, 1 hour at 212 F Scum test 9% 2%Barely passes. Does not pass.

1 75 m1. of the oil to be tested is measured into a dry 4 ounce samplebottle and the unstoppered bottle is maintained in an oven for 16 hoursat 212 F. The sample bottle is then removed from the oven, allowed tocool to approximately room temperature and the TagRobinson color oi thesample then determined and reported as the colorhold.

bodies from the oils such as sodium salts of naphthenic acids producedin prior treatment with an alkaline reagent and when a component of theheating oil of the present invention is not treated with an alkalinelreagent the filtration step, so far as that particular oil is concerned,may be omitted.

In order to illustrate further the beneficial effects obtained byprocessing heating oil fractions in accordance with the presentinvention,

several runs were made in which heating oil fractions, from the threesources mentioned before in the specification, were subjected to varioustreating procedures. In the rst run an acid treated and rerun heatingoil fraction from a thermal cracking operation, a heating oil fractionfrom crude petroleum, and a heating oil fraction from a catalyticcracking operation were blended together and then contacted with 40 B.caustic. After the caustic wash the heating oil was doctor sweetened,given a sodium polysulde and water wash and then filtered. Tests wereobtained on the filtered material. In a second run a heating oil.fraction from the same thermal It will be readily seen that the productobtained in accordance with the practice of the present invention in run4 is superior in quality to those obtained by the other handlingmethods. Special attention is directed to the vastly improved color ofthe products of run 4 as compared to the products of runs 1 and 2. Run 3did not contain any catalytically cracked material; therefore, it is notstrictly comparable with run 4. It will be noted, however, that thecolor stability, as reflected by the colorhold test of run 3, similar toruns 1 and 2, is vastly inferior to that of run 4. The other testslikewise reflect the superior product obtained by the practice of thepresent invention.

The superiority in quality of the product of the present invention isfurther indicated by tests under storage conditions of samples of thecomposition of the present invention and samples of heating oil finishedin accordance with a conventional procedure. The results of these testsare set out in Table II below. In this table the samples employed inruns 1 and 3 were finished in the same manner as the samples employed inrun 1 of Table I in that an acid treated and rerun heating oil fractionfrom a thermal cracking operation, a heating oil fraction from crudepetroleum and a heating oil fraction from a catalytic `crackingoperation were blended together, contacted with 40 B. caustic, doctorsweetened, Washed with sodium polysulde, washed with Water andsubsequently filtered. The samples employed for runs 2 and 4 wereprepared in the same Way as was the sample for run 4 of Table I in thatan acid treated and rerun heating oil from a, thermal cracking operationwas aclmiXed with a heating oil from a. crude petroleum,

the admixture caustic washed, doctor sweetened,r

polysulde washed and water washed and to this treated mixture was addeda heating oil fraction from a catalytic cracking operation and theresulting composition ltered. In other words, the samples used for runs2 and 4 represented the preferred embodiment of the present inventio-n.It may be pointed out that although the same treatment was given samples1 and 3, that of sample 1 was carried out in the laboratory and that ofsample 3 was carried out in plant operation and similarly sample 2 wastreated in the laboratory while sample 4 was obtained from a stocktreated in plant operation.

Table II Runs l 2 3 4 Inspections on finished heating Color,Tag-Robinson 10% 18 10 18% Colorhold, 16 hrs. at 212 F 9% 17% 7 14%Storage temperature Atms. Atms. Atms. Atms.

or, Tag-Robinson, alte Weeks storage. 10% 18 10 18% 2 Weeks storage-91/2 18 l0 17% 4 weeks storage.. 9% 16% 10 16% 6 Weeks storage 9V 16 9%15% necessary to obtain the several fractions processed as described.Likewise, the amount and strength of the treating reagents are not givenin describing the present invention. These amounts can be determined byexperimentation and may vary with the type of stock undergoingtreatment.

The nature and objects of the present invention having been describedand illustrated, what We wish to claim as new and useful and to secureby Letters Patent is:

A composition prepared for use as a distillatetype heating oilcomprising chemically unrefined catalytically cracked naphtha distillateand chemically reiined crude petroleum and thermally cracked naphthadistillates, said :composition boiling within the range of about 350 F.and '700 F. and having a Tag-Robinson color no less than of the order of15 after being subjected to storage under atmospheric temperature forapproximately siX weeks.

ARTIE'Q. CATO. GEORGE WASH. ALBERT J. SHMIDL.

REFERENCES CllTED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,360,272 Plummer Oct. 10, 19442,246,760 Ryan et al. June 24, 1941 2,315,935 Child Apr. 6, 19432,104,919 Whitney Jan. 11, 1938 2,252,082 Lloyd et al Api'. 12, 19412,048,371 Calderwood July 21, 1936 OTHER REFERENCES North Dakota Report1941, issued Aug. 1942, Bulletin #68, pages 58to 61.

